Subject: [Sip] Changing the To header

From: "Elwell, John" <[email-masked]>
Date: Thu, 10 Nov 2005 03:08:35 +0000

In yesterday's SIP session it was agreed to investigate the possibility of
changing the To header field URI in a response to a dialog-forming request.
To kick off this discussion, here are my thoughts.

A modified To header field URI in a response to a dialog-forming request can
indicate that the request has been retargeted. This would not be
authenticated, so if an authenticated called party identity is required it
would be necessary to ignore the modified To header field URI and wait for
an authenticated identity in a subsequent request from the called party.

One use case is in a closed environment, particularly where sips is used,
where transitive trust is used to give credibility to the unauthenticated
identity.

A second use case is to give a preliminary indication based on an identity
in a provisional response, to be replaced by an indication based on an
authenticated identity in the subsequent 2xx response.

Fire away.

John
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---

From: "Michael Hammer \(mhammer\)" <[email-masked]>
Date: Thu, 10 Nov 2005 14:53:25 -0500

Could you clarify what you mean by wait for an authenticated identity.
Is that an Auth-ID body or is it the implication that an endpoint
corrected the To: header or provided an additional P-header?
 
Mike

________________________________

	From: [email-masked] [mailto:[email-masked]] On
Behalf Of Elwell, John
	Sent: Wednesday, November 09, 2005 10:09 PM
	To: IETF SIP List
	Subject: [Sip] Changing the To header

	In yesterday's SIP session it was agreed to investigate the
possibility of changing the To header field URI in a response to a
dialog-forming request. To kick off this discussion, here are my
thoughts.

	A modified To header field URI in a response to a dialog-forming
request can indicate that the request has been retargeted. This would
not be authenticated, so if an authenticated called party identity is
required it would be necessary to ignore the modified To header field
URI and wait for an authenticated identity in a subsequent request from
the called party.

	One use case is in a closed environment, particularly where sips
is used, where transitive trust is used to give credibility to the
unauthenticated identity.

	A second use case is to give a preliminary indication based on
an identity in a provisional response, to be replaced by an indication
based on an authenticated identity in the subsequent 2xx response.

	Fire away. 

	John

---

From: "Elwell, John" <[email-masked]>
Date: Thu, 10 Nov 2005 20:34:22 +0000

Michael,
 
What I mean is a request in the reverse direction (e.g., UPDATE) carrying
the Identity header, which authenticates the From header.
 
John

  _____  

From: Michael Hammer (mhammer) [mailto:[email-masked]] 
Sent: 10 November 2005 19:53
To: Elwell, John; IETF SIP List
Subject: RE: [Sip] Changing the To header

Could you clarify what you mean by wait for an authenticated identity.  Is
that an Auth-ID body or is it the implication that an endpoint corrected the
To: header or provided an additional P-header?
 
Mike

  _____  

From: [email-masked] [mailto:[email-masked]] On Behalf Of
Elwell, John
Sent: Wednesday, November 09, 2005 10:09 PM
To: IETF SIP List
Subject: [Sip] Changing the To header

Fire away. 

John